During the 19th century, portions of the valley had been used variously for farming, as a salt works, as the location for several natural gas wells, and as a golf course. Just before World War I, the Regent Square Plan of homes (between Braddock, Trevanian and Hutchinson Avenues) was built fronting on the "big 100 acre Frick Forest that skirts along the eastern border of Squirrel Hill."

The land that now comprises the Regent Square Gateway site was originally patented by the Commonwealth to Abdiel McClure in 1788. It is speculated that the site already contained a grist mill that was about 200 feet downstream from Old Braddock Avenue. Historical records state that the grist mill was built in or around 1755 as an outpost from Ft. Duquesne. The location of the grist mill is likely buried beneath the parkway.

The land was purchased by John Swisshelm in 1808. At the time an old block house stood at the northwest corner of West Swissvale and Braddock Avenues. John Swisshelm built a stone barn in 1814 which stood on the northwest side of Braddock Avenue and Nine Mile Run Road. John Swisshelm lived on the farm

for the rest of his life and his son James continued after his death. James Swisshelm married Jane Grey Cannon, one of the country's most ardent abolitionists. The barn and grist mill had crumbled and fallen in by 1892. The old Swisshelm home burned down by 1904.

Henry Clay Frick's will deeded 159 acres to the City of Pittsburgh around Clayton Hill, site of the Frick Environmental Center, and endowed $2 million in trust to the City to maintain, improve and embellish the new park. A portion of these funds were used to purchase adjoining properties to expand the park. Two of the largest purchases were the Swisshelm Estate, extending the park up to old Braddock Avenue, and the Allegheny Country Club and Golf Course, extending from Beechwood Boulevard to Nine Mile Run. The latter purchase occurred in 1936 and expanded the park to its current size.

The Gateway site was envisioned as the Swisshelm entrance to Frick Park in 1930s park plans. Braddock Road and Nine Mile Run were moved to their current locations during construction of the parkway around 1950. Construction of the parkway and the Braddock Avenue interchange buried the remnants of the Swisshelm estate, including the remaining mill stones in Nine Mile Run.

Information from Historical Data: Pittsburgh Public Parks, compiled by Howard Stewart, under sponsorship of the Greater Pittsburgh Parks Association (Pittsburgh, PA 1943)

During the 19th century, portions of the valley had been used variously for farming, as a salt works, as the location for several natural gas wells, and as a golf course. Just before World War I, the Regent Square Plan of homes (between Braddock, Trevanian and Hutchinson Avenues) was built fronting on the "big 100 acre Frick Forest that skirts along the eastern border of Squirrel Hill." Promotional materials for the plan stated that this beautiful woodland has long been talked of as a future city park and persons who are well informed confidently assert that there is little doubt that eventually this valuable property will come into possession of the city as still another breathless spot for the people. Even as is it is, however,

it is a thing of beauty and a joy to natives of Regent Square and a royal playground for the children.

Henry Clay Frick's will deeded 159 acres to the City of Pittsburgh around Clayton Hill, site of the Frick Environmental Center, and endowed $2 million in trust to the City to maintain, improve and embellish the new park. A portion of these funds were used to purchase adjoining properties to expand the park. Two of the largest purchases were the Swisshelm Estate, extending the park up to old Braddock Avenue, and the Allegheny Country Club and Golf Course, extending from Beechwood Boulevard to Nine Mile Run. The latter purchase occurred in 1936 and expanded the park to its current size.

In 1928, construction commenced on the sewer trunk line through Frick Park to convey sewer from the upstream municipalities of Wilkinsburg, Swissvale and Edgewood to the Monongahela River. Various sewer additions, extensions, and improvements, including the Combined Sewer Outfall, occurred throughout the 1930s. Also, a number of employment relief projects benefited Frick Park, including shelters and walls, bowling greens, tennis courts, and plantings. In 1950 the Commercial Street Bridge over Nine Mile Run was completed. The Parkway East was completed soon thereafter.